anchorhandler
New member
Hehe, good point.
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How long should a diesel engine last?
- Thread starter pheran
- Start date
adarcy
New member
Re: err no !
Re <<so you could argue that the marine engine is better serviced>>
I say again 90% wear in first 5 mins from cold. So a high use or continuous use engine needs oil change + service by hours run but a typical leisure marine engine which has say 2 cold starts a day for 2 weekend days 30 W/e a year + 2 week holiday say 14 cold startsis going to spend a much larger part of its running time in the "wear zone". They only get serviced because of the deterioration of the oil over time. So, no way better serviced they may be if people changed the oil 3-4 times a year!
I also think people are missing the point about derating engines. Changing a fuel pump/rack/electronic control is EXACTLY the same as using less throttle. Diesels are not like petrols, the induction (especially turbo or supercharged) inject excess air and the bang is proportional to the amount of fuel injected. If you reduce the turbo boost, less will get in and an unreduced pump will then overfuel but reducing the throttle setting is just the same as having a reduced supply pump alteration. Both will limit the power, torque and stress on the engine and increase it's life. I agree with the rest that leisure users should RTFM, they clearly limit the %age time of high power use - areas that a restricted engine will never reach
But logically, a high performance diesel engine should be just as able to clock 10k hours as long as it is kept within the restriced power area because it's the same thing as continuous use engines but people just don't use them like that.
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Re <<so you could argue that the marine engine is better serviced>>
I say again 90% wear in first 5 mins from cold. So a high use or continuous use engine needs oil change + service by hours run but a typical leisure marine engine which has say 2 cold starts a day for 2 weekend days 30 W/e a year + 2 week holiday say 14 cold startsis going to spend a much larger part of its running time in the "wear zone". They only get serviced because of the deterioration of the oil over time. So, no way better serviced they may be if people changed the oil 3-4 times a year!
I also think people are missing the point about derating engines. Changing a fuel pump/rack/electronic control is EXACTLY the same as using less throttle. Diesels are not like petrols, the induction (especially turbo or supercharged) inject excess air and the bang is proportional to the amount of fuel injected. If you reduce the turbo boost, less will get in and an unreduced pump will then overfuel but reducing the throttle setting is just the same as having a reduced supply pump alteration. Both will limit the power, torque and stress on the engine and increase it's life. I agree with the rest that leisure users should RTFM, they clearly limit the %age time of high power use - areas that a restricted engine will never reach
But logically, a high performance diesel engine should be just as able to clock 10k hours as long as it is kept within the restriced power area because it's the same thing as continuous use engines but people just don't use them like that.
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duncan
Active member
Re:some of us....
I only ever use full throttle when (1) chasing Happy1 round the solent and (2) heading home form a long weekend in the bar with Barry and Forbsie.........../forums/images/icons/smile.gif
Seriously I don't find it relaxing and my normal crew (family) will not tolerate WOT at all. I woul dlove to think that my engine will last and last and last.
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I only ever use full throttle when (1) chasing Happy1 round the solent and (2) heading home form a long weekend in the bar with Barry and Forbsie.........../forums/images/icons/smile.gif
Seriously I don't find it relaxing and my normal crew (family) will not tolerate WOT at all. I woul dlove to think that my engine will last and last and last.
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anchorhandler
New member
Re: err no !
Hello Adarcy
Couldnt agree with you more....
incidentaly,most larger Cat's. MTU's, Rustons,Detroit diesel's all require major overhaul above the 10000hrs mark with some requiring this at 30000hrs. IN the heavy commercial sector, most engines will require a rebuild at around a minimum of 30000hrs and most going to 50000hrs. (i have a feeling i may be teaching you to suck eggs though!)
On the subject of de-rating.
I would be very suprised to find any commercial vessel afloat today that, when the throttles on the bridge are pushed hard over, the engines give 100%!! Its always nice to keep a little in reserve however the temptation to keep 'nudging' the throttles up is far too great for most to resist. its for this reason that the control system is set-up kind of like having a restriction under the accelerator of a car. The skipper thinks he has full power since the sticks are at max however........sounds like some people may find it a good idea to do similarly on theyre leisure boats.
By the way, if anyone is that worried about engine longevity, then buy and fit the Kenlowe pre-heater that is for sale in the private adds forum....its a good start and i would highly recomend them!
Simon
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Hello Adarcy
Couldnt agree with you more....
incidentaly,most larger Cat's. MTU's, Rustons,Detroit diesel's all require major overhaul above the 10000hrs mark with some requiring this at 30000hrs. IN the heavy commercial sector, most engines will require a rebuild at around a minimum of 30000hrs and most going to 50000hrs. (i have a feeling i may be teaching you to suck eggs though!)
On the subject of de-rating.
I would be very suprised to find any commercial vessel afloat today that, when the throttles on the bridge are pushed hard over, the engines give 100%!! Its always nice to keep a little in reserve however the temptation to keep 'nudging' the throttles up is far too great for most to resist. its for this reason that the control system is set-up kind of like having a restriction under the accelerator of a car. The skipper thinks he has full power since the sticks are at max however........sounds like some people may find it a good idea to do similarly on theyre leisure boats.
By the way, if anyone is that worried about engine longevity, then buy and fit the Kenlowe pre-heater that is for sale in the private adds forum....its a good start and i would highly recomend them!
Simon
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BrendanS
Well-known member
Re:some of us....
I'm getting confused by this talk about throttles. I thought they were a simple on/off switch? Am I to take it that they have variable settings?
<hr width=100% size=1>Utinam logica falsa tuam philisophiam totam suffodiant
I'm getting confused by this talk about throttles. I thought they were a simple on/off switch? Am I to take it that they have variable settings?
<hr width=100% size=1>Utinam logica falsa tuam philisophiam totam suffodiant
duncan
Active member
Re:some of us....
some (not all apparently)
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some (not all apparently)
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anchorhandler
New member
Re:some of us....
Sorry guys, didnt mean to generalise when i mentioned the "some people"
In fact i'm probably one of the bigest culprits going when it comes to accidentally knocking the throttles up......just gotta remember to let go of the mooring lines first!!! ..DOH!
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Sorry guys, didnt mean to generalise when i mentioned the "some people"
In fact i'm probably one of the bigest culprits going when it comes to accidentally knocking the throttles up......just gotta remember to let go of the mooring lines first!!! ..DOH!
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BrendanS
Well-known member
Re:some of us....
don't worry, we were just joking between friends, nought to do with your posts
<hr width=100% size=1>Utinam logica falsa tuam philisophiam totam suffodiant
don't worry, we were just joking between friends, nought to do with your posts
<hr width=100% size=1>Utinam logica falsa tuam philisophiam totam suffodiant
BarryH
Active member
Re:some of us....
I wouldn't worry too much about it Brendan, its a diesel thing. See the more you open them up the more they clank, rattle and rumble. Just use the smooth quiet power of your petrol.....no matter what the throttle setting
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I wouldn't worry too much about it Brendan, its a diesel thing. See the more you open them up the more they clank, rattle and rumble. Just use the smooth quiet power of your petrol.....no matter what the throttle setting
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duncan
Active member
Re:some of us....
that's part of it - I admit!
now the V6 Mercury OB on previous boat used to emit such an evocative sound at full chat.......and I will agree that V8s rock.
how can my poor 4 pot lump compete? At this point a lesser mortal would raise fuel consumption but I will resist..../forums/images/icons/smile.gif
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that's part of it - I admit!
now the V6 Mercury OB on previous boat used to emit such an evocative sound at full chat.......and I will agree that V8s rock.
how can my poor 4 pot lump compete? At this point a lesser mortal would raise fuel consumption but I will resist..../forums/images/icons/smile.gif
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BrendanS
Well-known member
Re:some of us....
I quite like the concept of adjustable throttle though. Would certainly make berthing easier. Hitting the pontoon at 44knts doesn't half rattle the windscreen!
<hr width=100% size=1>Utinam logica falsa tuam philisophiam totam suffodiant
I quite like the concept of adjustable throttle though. Would certainly make berthing easier. Hitting the pontoon at 44knts doesn't half rattle the windscreen!
<hr width=100% size=1>Utinam logica falsa tuam philisophiam totam suffodiant
D
Deleted User YDKXO
Guest
Re: err no !
OK, let's take your analysis and compare cold starts for marine engines and construction machine engines
I dont accept your calculation for the number of typical marine engine cold starts. I would say that average usage is more like 20 weekends a year plus a 14 day holiday and you can only have 1 cold start a day because any subsequent starts are warm starts. So that gives a total of 54 cold starts a year. Lets say that the typical marine engine requires a major rebuild after 15 yrs, thats 810 cold starts in its lifetime. Even if we take a 20yr service life, thats 1080 cold starts in its lifetime
A typical construction machine works maybe 200 days a year and thats 200 cold starts a year and the engine will last maybe 8 years and that makes 1600 cold starts during its lifetime, considerably more than a marine engine
So, clearly, the number of cold starts an engine experiences is not the only factor which affects service life although I agree it is a significant factor.
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OK, let's take your analysis and compare cold starts for marine engines and construction machine engines
I dont accept your calculation for the number of typical marine engine cold starts. I would say that average usage is more like 20 weekends a year plus a 14 day holiday and you can only have 1 cold start a day because any subsequent starts are warm starts. So that gives a total of 54 cold starts a year. Lets say that the typical marine engine requires a major rebuild after 15 yrs, thats 810 cold starts in its lifetime. Even if we take a 20yr service life, thats 1080 cold starts in its lifetime
A typical construction machine works maybe 200 days a year and thats 200 cold starts a year and the engine will last maybe 8 years and that makes 1600 cold starts during its lifetime, considerably more than a marine engine
So, clearly, the number of cold starts an engine experiences is not the only factor which affects service life although I agree it is a significant factor.
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MainlySteam
New member
Re: err no !
Just for the sake of clarity (not to teach egg sucking) a commercial engine will come from the factory (generally) with a lower rating than a pleasure engine ie it will produce less power regardless of throttle position. The operator will tell the naval architect at what percentage of Maximum Continuous Rating he wants for the performance he wants eg say 85% and that is usually linked to the operating cycle of the boat eg a fast harbour ferry may be rated higher than a trawler on the basis of its different duty cycle, and according to the service life he wants for the engine. The engines are then selected accordingly eg the desired service speed is attainable at the desired MCR % (at the desired throttle setting).
In a past life managing design approvals of small vessels for an Administration (ie a state), we allowed the use of pleasure rated engines in commercial vessels as long as the vessels service was appropriate (say a fast big game fishing charter motorboat which may wish to go fast to the fishing ground but then spends the rest of the day at low speeds) but along with the operating limits imposed for structural reasons (eg maximum operating speed and significant wave height) we always imposed a cycle condition on the engines eg "Engines not to be operated at more than x% of full throttle for more than y minutes/hours per 24 hours". Such limits are not normally necessary on commercially (lower) rated engines.
After all that repetitive pain, the reason it is important is that I often hear people with pleasure boats and even boatyard/boatbuilders' staff say of diesel engines in pleasure boats "You know your diesels like to be worked hard, don't pamper them if you want long life", which may be true as a general statement but it is also likely that ones pleasure boat engine is already working hard at quite a lot less than full throttle purely because it has been rated at a high power output when compared to the same engine in a commercial vessel. At full throttle it may be being thrashed and many do not seem to realise that.
I can see that with Brendan's two position throttle we will have to convert him to water jets /forums/images/icons/smile.gif.
John
<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by MainlySteam on 10/03/2004 22:33 (server time).</FONT></P>
Just for the sake of clarity (not to teach egg sucking) a commercial engine will come from the factory (generally) with a lower rating than a pleasure engine ie it will produce less power regardless of throttle position. The operator will tell the naval architect at what percentage of Maximum Continuous Rating he wants for the performance he wants eg say 85% and that is usually linked to the operating cycle of the boat eg a fast harbour ferry may be rated higher than a trawler on the basis of its different duty cycle, and according to the service life he wants for the engine. The engines are then selected accordingly eg the desired service speed is attainable at the desired MCR % (at the desired throttle setting).
In a past life managing design approvals of small vessels for an Administration (ie a state), we allowed the use of pleasure rated engines in commercial vessels as long as the vessels service was appropriate (say a fast big game fishing charter motorboat which may wish to go fast to the fishing ground but then spends the rest of the day at low speeds) but along with the operating limits imposed for structural reasons (eg maximum operating speed and significant wave height) we always imposed a cycle condition on the engines eg "Engines not to be operated at more than x% of full throttle for more than y minutes/hours per 24 hours". Such limits are not normally necessary on commercially (lower) rated engines.
After all that repetitive pain, the reason it is important is that I often hear people with pleasure boats and even boatyard/boatbuilders' staff say of diesel engines in pleasure boats "You know your diesels like to be worked hard, don't pamper them if you want long life", which may be true as a general statement but it is also likely that ones pleasure boat engine is already working hard at quite a lot less than full throttle purely because it has been rated at a high power output when compared to the same engine in a commercial vessel. At full throttle it may be being thrashed and many do not seem to realise that.
I can see that with Brendan's two position throttle we will have to convert him to water jets /forums/images/icons/smile.gif.
John
<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by MainlySteam on 10/03/2004 22:33 (server time).</FONT></P>
adarcy
New member
Re: Nitpick to Deleted User
First of all, I think we are agreeing on most of this stuff
but if you have another look at my post, I was specifically replying to
<<Re <<so you could argue that the marine engine is better serviced>> >>
not lifetime wear. I would gently suggest that a cold start followed by a 30 min run and then anchoring or tying up and emptying the contents of the food + booze fridges or going off to the boozer/restaurant (according to taste) often leads to 4-5 hours cooling down time so a second start is as near as dammit another cold start. Repeat the same the next day.
Never mind, what I was trying to suggest that my 94 or your 54 starts in 100 hours leisure use compares 200 cold starts for an engine that may reach 200 x 6-8 hours say 1400 hrs /year when you say it may be serviced (oil change anyway) every 250-500 hrs.
Therefore I cannot agree with you that a leisure engine
<<you could argue that the marine engine is better serviced>>
Off nitpicking, no one has picked up on the effect of short runs polluting the oil as it never gets hot enough to dry out/burn off pollutants compared with a nice steady 8hr run in truck or generator. I have only addressed the effect of the cold start but all these things are additive.
Do you think the population has had enough of this topic?
Anthony
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First of all, I think we are agreeing on most of this stuff
but if you have another look at my post, I was specifically replying to
<<Re <<so you could argue that the marine engine is better serviced>> >>
not lifetime wear. I would gently suggest that a cold start followed by a 30 min run and then anchoring or tying up and emptying the contents of the food + booze fridges or going off to the boozer/restaurant (according to taste) often leads to 4-5 hours cooling down time so a second start is as near as dammit another cold start. Repeat the same the next day.
Never mind, what I was trying to suggest that my 94 or your 54 starts in 100 hours leisure use compares 200 cold starts for an engine that may reach 200 x 6-8 hours say 1400 hrs /year when you say it may be serviced (oil change anyway) every 250-500 hrs.
Therefore I cannot agree with you that a leisure engine
<<you could argue that the marine engine is better serviced>>
Off nitpicking, no one has picked up on the effect of short runs polluting the oil as it never gets hot enough to dry out/burn off pollutants compared with a nice steady 8hr run in truck or generator. I have only addressed the effect of the cold start but all these things are additive.
Do you think the population has had enough of this topic?
Anthony
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D
Deleted User YDKXO
Guest
Re: Nitpick to Deleted User
Yes, I guess nobody's reading this anyway. I could have come back with yet more picknitting but being a gentleman, I'll let you have the last word
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Yes, I guess nobody's reading this anyway. I could have come back with yet more picknitting but being a gentleman, I'll let you have the last word
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anchorhandler
New member
Re: err no !
Thanks John.
I should have mentioned The MCR ratings in my previous post but didnt want to complicate things further...
My experience at the design/build stage is somewhat limited so i appreciate your usefull comments.
Not quite sure i can agree with "...."You know your diesels like to be worked hard, don't pamper them if you want long life", which may be true as a general statement ..." though but never mind, its been a good discussion.
Thanks
Simon
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Thanks John.
I should have mentioned The MCR ratings in my previous post but didnt want to complicate things further...
My experience at the design/build stage is somewhat limited so i appreciate your usefull comments.
Not quite sure i can agree with "...."You know your diesels like to be worked hard, don't pamper them if you want long life", which may be true as a general statement ..." though but never mind, its been a good discussion.
Thanks
Simon
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duncan
Active member
Re: Nitpick to Deleted User
no.../forums/images/icons/smile.gif
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no.../forums/images/icons/smile.gif
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